In the footage posted online on Sunday, a man wearing military gear is seen knife in hand slicing parts of a dead soldier's torso before turning to the camera and putting the heart in his mouth.
"I swear we will eat from your hearts and livers…," the man says referring to the Syria government soldiers.
Peter Bouckaert of the New York-based Human Rights Watch says the man has been identified as Abu Sakkar, a founder of the militant Farouq Brigade.
Abu Sakkar's identity has been confirmed by militant sources in Homs and by images of him in other videos wearing the same black jacket as in the latest clip and with the same rings on his fingers.
"The mutilation of the bodies of enemies is a war crime. But the even more serious issue is the very rapid descent into sectarian rhetoric and violence," Bouckaert said.
He added that in the unedited version of the film, Sakkar is heard telling his men to slaughter the Syrian soldiers and take their hearts out to eat them.
The footage has caused outrage among both supporters of President Bashar al-Assad and opposition figures.
Turmoil has gripped Sy ria since March 2011, and many people, including large numbers of Syrian security forces, have been killed in the unrest.